1. Field of the Invention
The present invention relates to a video on demand (VOD) transmission/reception method and system, and more particularly, to a VOD transmission/reception method and system using a divided transport stream (TS).
2. Description of the Related Art
Currently, due to broadened networks and developed broadcasting technologies, a video on demand (VOD) service is regarded as a new value-added business. The VOD service is a bidirectional service by which digital data such as movie, education, game, and shopping video data can be provided to a plurality of users at remote places by using a communication network. Video such as moving image data and audio data has a very large capacity even after being compressed. When the video data is transmitted through a network, a very large number of channel bandwidths requiring considerable costs have to be ensured. Thus, bandwidths need to be efficiently used in the VOD service.
The VOD service is divided into a true VOD (TVOD) service and a near VOD (NVOD) service according to a video transmission method. The TVOD service allows each viewer to select and view a desired program at a desired time, and provides various multimedia contents to viewers by using a unicast method. In spite of advantages as an interactive service, the TVOD service has disadvantages in that a large number of bandwidths are required because the viewers occupy transmission channels from a content server to the viewers' terminals, and thus a large amount of money is required to ensure the bandwidths. On the other hand, in spite of disadvantages of a non-interactive service and the viewers' waiting time, the NVOD service sequentially and repeatedly transmits one video program through a plurality of broadcasting channels. The NVOD service greatly reduces systematic costs by providing video data to a plurality of viewers through one video channel. The NVOD service requires a greatly less number of channels in comparison to the TVOD service. However, a large number of viewers cannot immediately view requested video data.
A current Internet protocol television (IPTV) service has traffic such as real-time broadcasting, TVOD transmission, and NVOD transmission. For example, in order to provide the TVOD service, a standard definition television (SDTV) requires a bit-rate of 2˜6 megabits per second (Mbps) and a high definition television (HDTV) requires a bit-rate of 6˜20 Mbps. Also, an additional bandwidth is required for each of service users. Obviously, the bit-rate can vary according to a compression method of corresponding contents. However, traffic of several gigabits per second (Gbps) naturally occurs to a content provider providing the TVOD service, in order to ensure the above bit-rate for each of the service users.
As a result, in consideration of all types of traffic including signals for a service, as well as content data, a huge amount of transmission traffic occurs in a whole backbone network when VOD services as well as the TVOD service are provided. Also, large variations in a transmission amount according to times when network users use a network are expected in the TVOD service. Accordingly, a method of expecting a required service amount and efficiently providing a TVOD service is demanded.